1. Field of the Invention
This invention is relates to an injection molding hot runner nozzle valve pin actuating apparatus, more particularly an actuating apparatus which simultaneously actuates a plurality of valve pins.
2. Related Art
In injection molding, when melt material is delivered to one or more mold cavities, it is sometimes desired to simultaneously actuate the valves of a plurality of nozzles that regulate the flow of the melt. This can be the case when there are many nozzles each serving its own cavity or when many nozzles serve one cavity.
An injection molding apparatus can include an array of nozzles that have valves that are simultaneously actuated via a yoke plate that is connected to one or more actuators; this is particularly useful in small pitch applications where there is not enough room between nozzles to accommodate individual actuators for each nozzle. One problem that can occur with this type of apparatus is yoke plate deflection caused by pressurized melt in the mold cavity pushing back on valve pins. This can result in larger than acceptable witness marks on the finished product or back-leakage of melt material from the cavity. This problem can affect any kind of injection molding where yoke plates are used.
Conventional solutions to yoke plate deflection include thickening the yoke plate. However, thickening the yoke plate adds to the stack height of the injection molding apparatus and adds significant cost to the injection molding apparatus.